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Radio Communications 101 - Off-Road Talk

Many people use portable radios to communicate while in the wilds. The three most common radios in use are UHF, VHF, and Citizen's Band or CB. The CB radio became popular in the 1970s when movies like Convoy, Smokey and the Bandit, and White Line Fever glamorized truckers and their use of the CB radio. They even wrote songs about it. CBs are inexpensive and easy to use but have limited range. They work well if you are traveling in a group and want to talk from truck to truck. They don't have a lot of power so they don't transmit very far. Generally, radios can transmit about 1 mile per watt. If you have a 5-watt CB, your range will be 5 miles in unobstructed terrain. The CB radio is in wide use and totally unregulated. If you have small children onboard, you might want to shut it off when you are traveling on the highway. Trucker's language can sometimes get questionable.

Moving up to longer-range models, you get into the UHF/VHF radio range. VHF stands for very high frequency. It is the most common in use so its bandwidth can get crowded. UHF stands for ultra high frequency. UHF radios can be more expensive. You have to understand how radio waves work to explain the differences. We won't burst your brains with a bunch of electronic mumbo jumbo; instead, we will keep it simple.

You can demonstrate how radio waves work with a length of rope. If you hold one end of a rope laid out straight in front of you and raise your arm up and then down, you will see a curl of rope travel away from you like a wave. The higher you move your arm up before bringing it down, the bigger or “wider” the curl is. That is bandwidth. You can move your arm faster, but the bandwidth stays the same as long as you move it to the same height. Let's say you are going as fast as you can, raising your arm all the way up before coming down. You can only create a certain amount of curls in one minute. The amount of curls created would be the frequency. In order to create a higher frequency, you would have to raise your arm lower, shortening each stroke. By doing that, you could raise your arm more times in a minute, increasing the frequency but at the same time decreasing the bandwidth.

The VHF's wider bandwidth travels farther in open terrain. It does well outdoors with little to no obstructions. Marine radios use VHF. UHF has a narrower bandwidth so it does a better job of going through walls, buildings, and other obstructions. UHF is the choice of police and others who operate in congested areas. If you notice, the door on your microwave has tiny holes in it. The holes allow you to see through the glass. Since the holes are small, the microwave's wide bandwidth (like VHF) cannot fit through them. The waves are instead bounced back toward your TV dinner. UHF's narrow bandwidth fits through openings in and around buildings better.

If you just want to listen in, you can get a scanner or receiver. It will let you hear what's going on. If you also want to transmit, you need a two-way radio. Once you determine whether you prefer VHF or UHF, you need to decide if you want a mobile truck-mounted radio or a portable handheld. Remember the power rule. A small handheld will have less power, which means less transmitting distance. Once you choose the type of radio you need and its power output, you then have a ton of options regarding headsets, microphones, and intercoms if you want to talk to your passenger in a loud racecar. There are all types of custom mounts and cables for installation; some CB radios even come with Bluetooth capabilities so you can use them hands-free.

Last but not least is your antenna. Not just any antenna will do. It is crucial to have your antenna tuned to work with your specific radio. The length is important, and longer is not always better. You will also need to determine where the antenna will be mounted. There are two types of antennae: grounded and non-grounded bases. If you are mounting to fiberglass or wood, you need a NGP or no ground plane antenna. It will have a ground cable that must be grounded to your vehicles chassis. Another common mistake is to take the extra length of antenna wire and just coil it up and stash it under the seat or behind a panel. That extra cable creates resistance, which can seriously degrade your signal. Whichever radio you decide to use, take some time to get educated on proper radio use and etiquette. Foul language should never be used on air. Remember, you are sharing the airwaves with everyone.